As is known, a singulator device receives at input groups of plane rectangular postal objects grouped in packs and feeds at output singulated postal objects, i.e., ones physically separated from each other.
For example, U.S. Pat. No. 4,634,328 (Mail Singulation System), WO91/15416 (Flat mail Singulation Apparatus), U.S. Pat. No. 4,171,130 (Control of withdrawal of flat items individually from a stack), and DE 101 40 497 illustrate singulator devices for postal objects.
Typically, the packs of approximately parallelepipedal postal objects slide along a horizontal plane of rest under the thrust of a drawing system that displaces the packs towards a singulator system designed to withdraw individually the postal objects that form a front end face of the pack. Typically, the packs move in a rectilinear direction of advance. The singulator system, for example, can comprise a motor-driven belt, which provides a vertical plane gripping portion associated to an intake device; the postal objects that form the front face of the pack come to bear upon the plane gripping portion that moves the objects in a direction perpendicular to that of advance, separating them from the pack.
In some processing modes, packs comprising postal objects having considerably different formats are fed to the singulator device, in particular packs comprising postal objects having standard dimensions, i.e., postal objects having maximum dimensions of up to 292 mm (length)×176 mm (height) alternating with packs comprising postal objects having extended dimensions, i.e., postal objects having maximum dimensions exceeding the standard format and up to the known C4 format (length 324 mm×height 229 mm) including types such as open magazines and poly-wrapped objects.
In said processing mode, it has been found by the applicant how the packs comprising postal objects with extended formats characterized by modest stiffness tend to “open up”, i.e., the postal objects set at the end of the pack bend towards the packs of standard postal objects adjacent thereto. In this way, said bent extended postal objects can assume positions not consonant with the extraction by the singulator system.